Mass–energy equivalence
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In physics, mass–energy equivalence is the relationship between mass and energy in a system's rest frame, where the two quantities differ only by a multiplicative constant and the units of measurement. The principle is described by the physicist Albert Einstein's formula: . In a reference frame where the system is moving, its relativistic energy and relativistic mass obey the same formula.
Task Force One, the world's first nuclear-powered task force. Enterprise, Long Beach and Bainbridge in formation in the Mediterranean, 18 June 1964. Enterprise crew members are spelling out Einstein's mass–energy equivalence formula E = mc2 on the flight deck.
In the revised English edition of Isaac Newton's Opticks, published in 1717, Newton speculated on the equivalence of mass and light.
Photo of Albert Einstein in 1921
Momentum
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In Newtonian mechanics, momentum is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction. If m is an object's mass and v is its velocity, then the object's momentum p is:
Momentum of a pool cue ball is transferred to the racked balls after collision.
Ibn Sīnā (980–1037)
René Descartes (1596–1650)
Christiaan Huygens (1629–1695)